1. Field of the Invention
The present disclosure generally relates to a sheet transport device and an image forming device including a sheet transport device. More specifically, the present disclosure relates to a sheet transport device adapted for use in an image forming device and including a sheet guiding member which is divided into plural member portions and arranged to guide transporting of a sheet by sheet transporting units in the image forming device. The image forming device may use an inkjet printing process or an electrophotographic printing process for image formation and may include printers, copiers, facsimile devices, plotters, multi-function peripherals, etc.
2. Description of the Related Art
Among image forming devices including printers, copiers, facsimile devices, plotters, multi-function peripherals, etc., there is an ink-jet printing device which ejects ink from a printing head to a sheet (which may include various print media, such as a copy sheet, a plastic film sheet, etc.) so that an image is formed on the sheet. A sheet transport device for use in this ink-jet printing device is known. In the sheet transport device, a sheet is supported and transported by using a platen member (or a sheet guiding member) which is divided into plural member portions along a main scanning direction of the printing head (which direction is perpendicular to a sheet transporting direction). The transporting of the sheet is guided by the platen member described above.
For example, Japanese Laid-Open Patent Publication No. 2011-110844 discloses an improvement technology of an ink-jet printing device. This ink-jet printing device can easily perform adjustment of a clearance between the printing head and the platen (which will be called a head-to-platen clearance) throughout the width of the platen with high precision. This ink-jet printing device can easily perform proper adjustment of the head-to-platen clearance for several printing sheets having different thicknesses throughout the width of the platen.
Specifically, Japanese Laid-Open Patent Publication No. 2011-110844 teaches the following features of the ink-jet printing device. As shown in FIGS. 2 and 3 of Japanese Laid-Open Patent Publication No. 2011-110844, a platen member for supporting a print medium is divided along a main scanning direction of a printing head into plural platen member portions. These platen member portions of the platen member are independently movable relative to the printing head in the direction in which they move close to or apart from the printing head. Each platen member portion is located in a position at a predetermined distance from the printing head by a locating unit which moves in a direction toward a guide shaft, and the position of each platen member portion is held by a platen holding mechanism. The head-to-platen clearance between the printing head and the platen member is adjusted by locating the position of each platen member portion held by the platen holding mechanism by using the locating unit.
However, according to the teaching of Japanese Laid-Open Patent Publication No. 2011-110844, in order to secure the accuracy of the position of each platen member portion, it is necessary to carry out the machining and assembling of the chassis for mounting the platen holding mechanism with a very high level of accuracy.